The present disclosure pertains to devices and methods for endoscopically ligating natural or artificial structures. Ligation is the act of making a ligature (tie). In medicine, a ligature is a device, similar to a tourniquet, usually of thread or string, tied around a limb, blood vessel or similar structure to restrict blood flow. For example, a ligature can be used for tumor strangulation, carried out before removal. A ligature can also be defined as a constricting or compressing device used to control venous and arterial circulation to an extremity for a period of time. Pressure is applied circumferentially upon the skin and underlying tissues of a limb; this pressure is transferred to the walls of vessels, causing them to become temporarily occluded. In surgery, the term “ligate” has come to mean the tying off or constriction of vessels, ducts or other tissue to prevent bleeding or leaking.
In open surgery and in extracorporeal applications a ligature can be easily constructed and applied. For example a surgeon's hands can manipulate a suture length onto and around a vessel or limb. This suture length can then be tied to constrict and fixed in place with a knot.
In laparoscopy, one common way to ligate tissue is to use multiple laparoscopic graspers in conjunction with suture. This technique consists of an opposing jaw grasping tip mounted on an elongated rigid shaft with proximal control handles. One or more of these are used through access points at positions relative to each other to allow complementary interaction. The instruments are used analogous to multiple hands to acquire, position, and tie suture in the form of a constricting knotted assembly. This is a skill intensive method that can be particularly challenging in the hands of a less experienced practitioner or in locations where access and/or visualization is difficult.
Alternatively, the ligation is augmented or simplified by eliminating the laparoscopic knot tying step, in place of which the knot is tied extracorporeally and slid into position. A knot delivery device that is used for these types of laparoscopic procedures is the Quik-Stitch™ endoscopic suturing system offered by Pare Surgical, Inc. Another simplification is using a clip or knot replacement device.
A widely utilized form of ligature in surgery, both open or laparoscopic, is a clip. Most conventional clips consist of a piece of metal wire or strip formed into a “V” or “U” shape. These are loaded into activatable/closable jaws of a clip delivery device, such as the device 50 illustrated in FIGS. 1A-B and 2. In the open state the clip 52 and delivery jaws 54 are positioned onto the tissue T to be ligated. The device is positioned in such a way so that the arms of the clip 52 are on either side of the target site. The jaws 54 are then closed under control of an actuation device associated with the device handle 56. This squeezes both clip 52 and tissue T into a pinched off configuration. The clip 52 is permanently deformed in the pinched configuration thus maintaining the ligature. Multiple clips are often used. Often the delivery jaws 54 are configured at a slight angle to the longitudinal axis of the instrument shaft to aid in visualization and positioning. This type of device is available in single fire/reloadable instruments and multi-fire instruments.
Clips and clip applier devices have a number of limitations. First, there are limitations on clip size. Because the clips are pre-shaped open they can be no wider than the size of the entry port/trocar minus the room necessary for the jaws of the delivery device. For example, a 10 mm trocar compatible clip applier may have jaws that require 2 mm of thickness, thus reducing the potential opening space “H” of the clip to 8 mm. It would be desirable to have a clip that is capable of expanding wider than the shaft size “S” of the delivery tool.
Second, the clip needs to be permanently deformed so the delivery tool must be able to deliver sufficient closing force. This becomes increasingly challenging for an elongated, flexible delivery device.
Third, the clip does not actually encircle the material to be ligated. Therefore, there is a potential for the clip to slip along the vessel or to be dislodged completely, lessening or eliminating the ligating effect.
More recently, devices have been constructed that address some of the limitations of the conventional ligation clips. One example of such a device is the Hem-o-Lok™ ligation system offered by Teleflex Medical. The Hem-o-Lok™ device is a hinged plastic clip that snaps closed to form a closed path compressed loop.
In endoscopic applications it is more difficult to gain the exposure and maneuverability necessary to apply a suture or clip. Also, it is more difficult to handle the suture precisely for proper tensioning and knotting using endoscopic instruments. This is difficult enough in laparoscopy where the instruments are rigid and can be used at alternate engagement angles from the various trocar sites. The difficulty increases even more in endoscopic environments where the instruments are long, flexible, and may be working through lengthy, tortuous pathways.